Disability affects as much as 17 percent of the adult population in the US and the majority of these individuals suffer both chronic medical conditions and psychiatric disorders. In combination, the impairments that accompany these disorders synergistically intensify any disability. Parkinson's disease (PD), a progressive neurodegenerative disorder, produces marked impairments of motor function and significant disability. However, the majority of PD patients also experience emotional and cognitive impairments, yet little is known about the contribution of these impairments to disability. In addition, disability assessment in PD has focused narrowly on self-care, ignoring other important areas such as work performance. It is unknown, for example, whether withdrawal from the workforce among PD patients is more closely tied to emotional and cognitive impairments than to decrements in motor function. The aim of this project is to assess impairments in motor, cognitive and emotional function and the accompanying disabilities, longitudinally, in individuals with PD, to understand how the impairments contribute to disability and how psychiatric disorders produce excess disability in these patients. Specifically we will examine performance on quantitative motor tests and cognitive tests of memory, attention and executive function. Psychiatric symptom occurrence and severity, clinical diagnosis, and temperament will also be examined. Disability assessment will include the areas of physical, social and occupational functioning as well as perceived quality of life, utilizing clinical interview, performance evaluation, vocational testing and informant interview. Participants will include 100 non-demented individuals with PD, 65 years of age or younger. Approximately equal numbers of males and females will be enrolled. All participants will be evaluated yearly, four times during the course of the project. Investigation into the full range of disability found in PD, and an understanding of the contribution all impairments play in increasing disability, will enable us to develop strategies to improve the care of these patients. It will also provide information to guide interventions to decrease the level of disability suffered by those with PD.